Computes the log transformation, including its inverse and the first two derivatives.
loge(theta, bvalue = NULL, inverse = FALSE, deriv = 0,
short = TRUE, tag = FALSE)
negloge(theta, bvalue = NULL, inverse = FALSE, deriv = 0,
short = TRUE, tag = FALSE)
logneg(theta, bvalue = NULL, inverse = FALSE, deriv = 0,
short = TRUE, tag = FALSE)Numeric or character. See below for further details.
See Links.
Details at Links.
The following concerns loge.
For deriv = 0, the log of theta, i.e., log(theta)
when inverse = FALSE, and if inverse = TRUE then
exp(theta).
For deriv = 1, then the function returns
d eta / d theta as a function of theta
if inverse = FALSE,
else if inverse = TRUE then it returns the reciprocal.
The log link function is very commonly used for parameters that
are positive.
Here, all logarithms are natural logarithms, i.e., to base \(e\).
Numerical values of theta close to 0 or out of range
result in
Inf, -Inf, NA or NaN.
The function loge computes
\(\log(\theta)\) whereas negloge computes
\(-\log(\theta)=\log(1/\theta)\).
The function logneg computes
\(\log(-\theta)\), hence is suitable for parameters
that are negative, e.g.,
a trap-shy effect in posbernoulli.b.
McCullagh, P. and Nelder, J. A. (1989) Generalized Linear Models, 2nd ed. London: Chapman & Hall.
Links,
explink,
logit,
logc,
loglog,
log,
logoff,
lambertW,
posbernoulli.b.
# NOT RUN {
loge(seq(-0.2, 0.5, by = 0.1))
loge(seq(-0.2, 0.5, by = 0.1), bvalue = .Machine$double.xmin)
negloge(seq(-0.2, 0.5, by = 0.1))
negloge(seq(-0.2, 0.5, by = 0.1), bvalue = .Machine$double.xmin)
# }
# NOT RUN {
logneg(seq(-0.5, -0.2, by = 0.1))
# }
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